1. Field of the Invention
The present invention relates to a compact solid-state imaging device, an image pick-up device using the solid-state imaging device, an endoscope apparatus or capsule-type endoscope apparatus using the solid-state imaging device or the image pick-up device, and a method for manufacturing the solid-state imaging device.
2. Description of the Related Art
Conventionally, a solid-state imaging device of which an example is shown in FIG. 11 has been known. The solid-state imaging device shown in FIG. 11 has a solid-state imaging element chip 151, to which optical glass 152 has been glued, die-bonded to a ceramic substrate 154, with electrode pads 153 provided on the perimeter of the solid-state imaging element chip 151 and connecting pads 155 provided on the edge upper face of the ceramic substrate 154 electrically connected by wire bonding with bonding wire 156. The connecting pads 152 are electrically connected with external leads 157 within the ceramic substrate 154 by unshown wiring, thereby assembling a solid-state imaging device capable of driving solid-state imaging elements via the external leads 157 or acquiring photo-reception signals.
On the other hand, solid-state imaging devices used for medical-purpose endoscopes and the like must be small in size, in order to reduce the diameter of the insertion portion of the endoscope. FIG. 12 illustrates a plan view of the solid-state imaging device shown in FIG. 11, whereby it can be understood that solid-state imaging devices with such configurations consume a wide area for the region to perform wire bonding, which goes against the object of reducing diameter.
To deal with this, Japanese Unexamined Patent Application Publication No. 8-148666 proposes a solid-state imaging device whereby reduction in size is realized by means of a flexible board. FIG. 13 illustrates the solid-state imaging device disclosed in this Publication. In FIG. 13, electrode pads 164 which have bumps 170 provided on the perimeter of the imaging region 163 of the solid-state imaging element chip 161, and leads 173 on the flexible board 166, are connected using an anisotropic conductive film 165, and a transparent cap 168 is fixed on the upper face of the flexible board 166 using an adhesive resin 167. The portion of the flexible board 166 corresponding to the imaging region 163 of the solid-state imaging element chip 161 is cut out, thereby forming a space 174 between the solid-state imaging element chip 161 and the cap 168. This space 174 is sealed off by the anisotropic conductive film 165 and the adhesive resin 167.
According to the solid-state imaging device configured thus, the size thereof can be readily reduced while maintaining the same level of image pick-up properties and reliability.
However, the conventionally-proposed solid-state imaging device has the following problems. First, viewing this arrangement from above shows that the bent portion of the flexible board still requires a certain amount of area, which obstructs reducing in diameter. Further, there is the need to assemble the diced and separated optical sensor substrates (solid-state imaging element chips), the optical glass (cap), and the individual flexible boards, and moreover there is the need to bend the flexible boards back following assembly, resulting in very poor ease-of-assembly.
Also, at the time of assembly, separated parts need to be handled for at least the optical sensor substrates (solid-state imaging element chips) and the optical glass (cap), which is troublesome. Also, the photo-reception portion (imaging region) of the optical sensor substrate (solid-state imaging element chip) is often exposed to the ambient atmosphere, often leading to defective imaging due to foreign matter adhering to the photo-reception portion or drying marks of cleansing fluids and the like remaining on the photo-reception portion, which has been a factor in reducing yield.
Further, in recent years, there has been demand for reducing of the solid-state imaging device in the thickness direction, besides the reduction in the area as described above. In such cases, the optical sensor substrate can be mechanically, physically, or chemically polished, but the polishing must be performed supporting the photo-reception portion of the optical sensor substrate (solid-state imaging element chip), which also often leads to defective imaging due to foreign matter adhering to the photo-reception portion or drying marks of cleansing fluids and the like remaining on the photo-reception portion, and has been a factor in reducing yield.
The present invention has been made in order to solve the above-described problems of conventional solid-state imaging devices, and accordingly, it is an object of the present invention to provide a solid-state imaging device and a manufacturing method thereof suitable for mass-production, wherein both reduction in size and improved yield can be achieved, and excellent ease of assembly and work is realized.